U.S. patent application number 16/273171 was filed with the patent office on 2020-02-06 for image reading device.
This patent application is currently assigned to FUJI XEROX CO., LTD.. The applicant listed for this patent is FUJI XEROX CO., LTD.. Invention is credited to Shota FUNAKI, Masaki HACHISUGA.
Application Number | 20200045195 16/273171 |
Document ID | / |
Family ID | 69229291 |
Filed Date | 2020-02-06 |
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United States Patent
Application |
20200045195 |
Kind Code |
A1 |
HACHISUGA; Masaki ; et
al. |
February 6, 2020 |
IMAGE READING DEVICE
Abstract
An image reading device includes at least one reference portion
that is provided in a reading area of a reading unit provided with
a moving mechanism, a memory unit that stores, as an initial value,
positional data of the reference portion that is read by the
reading unit, an acquisition unit that reads the positional data of
the reference portion and acquires a displacement amount of the
read positional data from the initial value, and an error handling
unit that performs error handling when the displacement amount
exceeds a predetermined value.
Inventors: |
HACHISUGA; Masaki;
(Kanagawa, JP) ; FUNAKI; Shota; (Kanagawa,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
FUJI XEROX CO., LTD. |
Tokyo |
|
JP |
|
|
Assignee: |
FUJI XEROX CO., LTD.
TOKYO
JP
|
Family ID: |
69229291 |
Appl. No.: |
16/273171 |
Filed: |
February 12, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04N 1/053 20130101;
H04N 1/00795 20130101; H04N 2201/04743 20130101; H04N 2201/0081
20130101; H04N 1/00615 20130101 |
International
Class: |
H04N 1/00 20060101
H04N001/00; H04N 1/053 20060101 H04N001/053 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 1, 2018 |
JP |
2018-144767 |
Claims
1. An image reading device comprising: at least one reference
portion that is provided in a reading area of a reading unit
provided with a moving mechanism; a memory unit that stores, as an
initial value, positional data of the reference portion that is
read by the reading unit; an acquisition unit that reads the
positional data of the reference portion and acquires a
displacement amount of the read positional data from the initial
value; and an error handling unit that performs error handling when
the displacement amount exceeds a predetermined value.
2. An image reading device comprising: at least one reference
portion that is provided in a reading area of a reading unit that
includes a moving mechanism; a memory unit that stores, as an
initial value, positional data of the reference portion that is
read by the reading unit; an acquisition unit that reads the
positional data of the reference portion and acquires a
displacement amount of the read positional data from the initial
value; and a correction unit that corrects, based on the
displacement amount, read data obtained by reading a reading
target.
3. The image reading device according to claim 1, wherein the at
least one reference portion includes a plurality of reference
portions.
4. The image reading device according to claim 3, wherein the
plurality of reference portions are parallel to each other.
5. The image reading device according to claim 2, wherein the
reference portion includes a first reference portion that is
provided on a first side of a scanning direction of the reading
unit and a second reference portion that is provided on a second
side of the scanning direction of the reading unit, and wherein,
when the correction unit corrects the read data, which has been
read between the first reference portion and the second reference
portion, based on the displacement amount, the correction unit
corrects the read data by using a complemented displacement amount
complemented based on a relationship between a separation distance
from the first reference portion to the second reference portion
and a distance from the first reference portion or the second
reference portion to the read data to be corrected.
6. The image reading device according to claim 1, wherein the
reference portion includes an edge of an abutting portion against
which the reading target is caused to abut so as to be
positioned.
7. The image reading device according to claim 1, wherein the
reference portion includes a reference line provided in the reading
area.
8. The image reading device according to claim 7, wherein the
reference line is provided in such a manner as to be located in a
region outside an edge of the reading target having a readable
document size in a state where the reading target is set at a
predetermined position.
9. The image reading device according to claim 7, wherein the
reference line is provided on a glass surface on which the reading
target is to be placed.
10. The image reading device according to claim 7, wherein the
reference line is provided on a covering that is to be placed above
the reading target.
11. The image reading device according to claim 7, wherein the
reference line includes a main reference line extending in a
direction of movement of the moving mechanism and an auxiliary
reference line extending in a direction crossing the direction in
which the main reference line extends.
12. The image reading device according to claim 7, wherein the
reference line is provided on a rear surface of an abutting portion
against which the reading target is caused to abut so as to be
positioned.
13. An image reading device comprising: at least one reference
portion provided in a reading area of a reading unit provided with
a moving mechanism; memory means for storing, as an initial value,
positional data of the reference portion that is read by the
reading unit; acquisition means for reading the positional data of
the reference portion and acquiring a displacement amount of the
read positional data from the initial value; and error handling
means for performing error handling when the displacement amount
exceeds a predetermined value.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is based on and claims priority under 35
USC 119 from Japanese Patent Application No. 2018-144767 filed Aug.
1, 2018.
BACKGROUND
(i) Technical Field
[0002] The present disclosure relates to an image reading
device.
(ii) Related Art
[0003] An image reading device described in Japanese Unexamined
Patent Application Publication No. 11-355513 includes a
main-scanning-direction reference mark that is formed in a
physical-length pattern, which functions as a reference in a main
scanning direction at a position that is on the same plane as an
image reading surface of a document table and that is outside of an
effective image region. The main-scanning-direction reference mark
provides information related to a reading magnification by being
read by a solid-state imaging device. The image reading device
calculates a reading magnification in the actual main scanning
direction on the basis of a predetermined length X of the
main-scanning-direction reference mark and length information Y
that is acquired as a result of the solid-state imaging device
reading the main-scanning-direction reference mark. The image
reading device automatically corrects, in accordance with the
calculation result, the reading magnification at which a document
is read in the main scanning direction.
[0004] In an image reading device described in Japanese Unexamined
Patent Application Publication No. 9-284479, two straight lines
each having a thickness of 0.3 mm are provided directly behind a
white reference plate for shading correction in such a manner as to
be parallel to each other in a subscanning direction. The ratio of
the distance between the marks stored in memory at the time of
performing a first scan operation to the distance between the marks
stored in the memory at the time of performing a second scan
operation is equal to a value obtained by multiplying a
magnification error caused by a printer and a magnification error
caused by a scanner. The image reading device performs
magnification adjustment on the basis of this value.
SUMMARY
[0005] Aspects of non-limiting embodiments of the present
disclosure relate to suppressing acquisition of an image that is
distorted due to deformation of a device compared with a case where
an image is acquired without using positional data of a reference
portion when the image is read.
[0006] Aspects of certain non-limiting embodiments of the present
disclosure overcome the above disadvantages and/or other
disadvantages not described above. However, aspects of the
non-limiting embodiments are not required to overcome the
disadvantages described above, and aspects of the non-limiting
embodiments of the present disclosure may not overcome any of the
disadvantages described above.
[0007] According to an aspect of the present disclosure, there is
provided an image reading device including at least one reference
portion that is provided in a reading area of a reading unit
provided with a moving mechanism, a memory unit that stores, as an
initial value, positional data of the reference portion that is
read by the reading unit, an acquisition unit that reads the
positional data of the reference portion and acquires a
displacement amount of the read positional data from the initial
value, and an error handling unit that performs error handling when
the displacement amount exceeds a predetermined value.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] Exemplary embodiments of the present disclosure will be
described in detail based on the following figures, wherein:
[0009] FIG. 1 a schematic diagram illustrating a configuration of
an image reading device according to a first exemplary
embodiment;
[0010] FIG. 2 is a perspective view illustrating a reading unit of
the image reading device according to the first exemplary
embodiment;
[0011] FIG. 3 is a diagram illustrating a top surface of the image
reading device according to the first exemplary embodiment;
[0012] FIG. 4 is a diagram illustrating a straight line to be read
has been captured in a distorted state;
[0013] FIG. 5 is a flowchart illustrating an operation of the image
reading device according to the first exemplary embodiment;
[0014] FIG. 6 is a diagram used for describing an operation of the
image reading device according to the first exemplary
embodiment;
[0015] FIG. 7 is a diagram used for describing an operation that is
performed subsequently to the operation illustrated in FIG. 6;
[0016] FIG. 8 is a graph illustrating results of a longitudinal
linearity test using the image reading device according to the
first exemplary embodiment;
[0017] FIG. 9 is a diagram illustrating a reading target that is
used in a right-angle test using the image reading device according
to the first exemplary embodiment;
[0018] FIG. 10 is a graph illustrating results of the right-angle
test using the image reading device according to the first
exemplary embodiment;
[0019] FIG. 11 is a diagram illustrating a reading target that is
used in an oblique linearity test using the image reading device
according to the first exemplary embodiment;
[0020] FIG. 12 is a graph illustrating results of the oblique
linearity test using the image reading device according to the
first exemplary embodiment;
[0021] FIG. 13 is a diagram illustrating a grid sample that is used
in an application;
[0022] FIG. 14 is a diagram illustrating a top surface of an image
reading device according to a second exemplary embodiment;
[0023] FIG. 15 is a diagram illustrating an operation of the image
reading device according to the second exemplary embodiment by an
arithmetic expression;
[0024] FIG. 16 is a diagram used for describing an operation of the
image reading device according to the second exemplary
embodiment;
[0025] FIG. 17 is a diagram illustrating a top surface of an image
reading device according to a third exemplary embodiment; and
[0026] FIG. 18 is a diagram illustrating a top surface of an image
reading device according to a fourth exemplary embodiment.
DETAILED DESCRIPTION
First Exemplary Embodiment
[0027] An image reading device 10 according to a first exemplary
embodiment will be described below with reference to the
drawings.
[0028] The image reading device 10 includes an image reading
processing unit 14 that reads an image formed on a surface of a
reading target 12 and a covering 16 that covers a top surface of
the image reading processing unit 14. A rear edge of the covering
16 is supported on the image reading processing unit 14 via a hinge
(not illustrated), and the covering 16 is configured to be in a
state of covering the top surface of the image reading processing
unit 14 or in a state of exposing the top surface.
[0029] The image reading processing unit 14 has a function of
reading a surface of a document that is the reading target 12
placed on a platen glass 18. As illustrated in FIG. 2, a reading
unit 22 that includes a moving mechanism 20 is disposed in in a
housing 14A of the image reading processing unit 14.
[0030] As illustrated in FIG. 1, the reading unit 22 includes a
full-rate carriage 24 that captures image information by using
light while moving along a longitudinal direction, which is a
reading direction in which the image reading processing unit 14
reads the reading target 12 and a half-rate carriage 26 that
changes an optical path L from the full-rate carriage 24. The
reading unit 22 further includes an imaging lens 28 through which
light passes after the optical path L has been changed by the
half-rate carriage 26 and a charge coupled device (CCD) image
sensor 30 that receives the light that has passed through the
imaging lens 28.
[0031] As illustrated in FIG. 2, the moving mechanism 20 of the
reading unit 22 includes a drive motor 32 and a drive shaft 36 that
is coupled to an output shaft 32A of the drive motor 32 via a belt
34. The drive shaft 36 extends in a transverse direction that is a
direction crossing the reading direction, in which the image
reading processing unit 14 reads the reading target 12, and drive
pulleys 38 are provided at the end portions of the drive shaft
36.
[0032] Drive wires 40 are wound around the drive pulleys 38. Each
of the drive wires 40 extending toward a first side NHI in the
longitudinal direction is bent toward a corresponding one of the
drive pulleys 38 via one of first-side fixed pulleys 42 each of
which is supported on the housing 14A via a rotary shaft. The drive
wires 40 bent by their respective first-side fixed pulleys 42 are
bent by drive pulleys 44, and ends of the drive wires 40 bent by
their respective drive pulleys 44 are fixed to the housing 14A.
[0033] Note that the drive wires 40 extending from their respective
drive pulley 38 toward a second side NHT in the longitudinal
direction are bent by second-side fixed pulleys 46 and then wound
around their respective drive pulleys 44.
[0034] Brackets 24A that extend from end portions of the full-rate
carriage 24 are each fixed to a portion of one of the drive wires
40, the portion being located between one of the first-side fixed
pulleys 42 and a corresponding one of the drive pulleys 44. In
addition, each of the drive pulleys 44 is rotatably supported by
one of support plates 26A that extend from the end portions of the
half-rate carriage 26.
[0035] As a result, each of the carriages 24 and 26 is caused to
move in the longitudinal direction by the drive wires 40 while
being supported by the drive wires 40. In addition, the moving
speed of the half-rate carriage 26 is one-half of the moving speed
of the full-rate carriage 24.
[0036] As illustrated in FIG. 1, the full-rate carriage 24 includes
an illumination unit 24B provided with a light source that radiates
light onto the reading target 12 and a diffuse-reflecting member
24C that reflects the light emitted by the illumination unit 24B
while diffusing the light toward the reading target 12. The
full-rate carriage 24 further includes a first mirror 24D that
reflects light that is reflected by the reading target 12 toward
the half-rate carriage 26.
[0037] The half-rate carriage 26 includes a second mirror 26B and a
third mirror 26C that guide light obtained from the full-rate
carriage 24 to the CCD image sensor 30 via the imaging lens 28. As
a result, the CCD image sensor 30 forms an image by using image
information acquired by the full-rate carriage 24, and the formed
image is obtained as image data.
[0038] The illumination unit 24B, the diffuse-reflecting member
24C, and the first mirror 24D of the full-rate carriage 24 extend
in the transverse direction of the image reading processing unit
14. In addition, the second mirror 26B and the third mirror 26C of
the half-rate carriage 26, the imaging lens 28, and the CCD image
sensor 30 extend in the transverse direction of the image reading
processing unit 14. Accordingly, the CCD image sensor 30 acquires
image information of the reading target 12 in the transverse
direction, and the transverse direction will be referred to as a
main scanning direction SH.
[0039] As illustrated in FIG. 2, the full-rate carriage 24 and the
half-rate carriage 26 are caused to move in the longitudinal
direction of the image reading processing unit 14 by the moving
mechanism 20, so that the image information of the reading target
12 in the longitudinal direction is acquired. The longitudinal
direction will be referred to as a subscanning direction FH, and
the subscanning direction FH crosses the main scanning direction
SH.
[0040] As illustrated in FIG. 1, the reading unit 22 includes a
controller 48 that controls the operation of the reading unit 22
and an image processing unit 50 that processes image data acquired
by the CCD image sensor 30. The controller 48 controls the drive
motor 32 of the moving mechanism 20, the illumination unit 24B, and
so forth, and the image processing unit 50 forms image data by
using data from the CCD image sensor 30 and processes the image
data.
[0041] FIG. 3 is a diagram illustrating the top surface of the
image reading processing unit 14 in the image reading device 10 and
illustrates a state in which the covering 16 has been removed from
the image reading processing unit 14.
[0042] The top surface of the image reading processing unit 14 is
formed in a rectangular shape and is provided with the platen glass
18 that has a rectangular shape. As illustrated in FIG. 2, the
reading unit 22 is disposed below the platen glass 18, and the
carriages 24 and 26 of the reading unit 22 extend in the transverse
direction, which is the main scanning direction SH. In addition,
each of the carriages 24 and 26 moves in the longitudinal
direction, which is the subscanning direction FH.
[0043] An opaque main-scanning-direction abutting portion 52 is
disposed on the platen glass 18 on a first side THI in the
transverse direction. The main-scanning-direction abutting portion
52 is formed of a plate-shaped member extending in the longitudinal
direction of the image reading processing unit 14 (the subscanning
direction FH), and the main-scanning-direction abutting portion 52
is formed so as to have a thickness larger than that of the platen
glass 18.
[0044] An edge 52A of the main-scanning-direction abutting portion
52 that is located on the side of the platen glass 18 protrudes
upward further than a glass surface 18A of the platen glass 18
does. A document, which is the reading target 12, is positioned by
causing a first side 12A of the document to abut against the edge
52A of the main-scanning-direction abutting portion 52, so that the
reading target 12 may be arranged at a predetermined position in
the main scanning direction SH.
[0045] An opaque subscanning-direction abutting portion 54 is
disposed on the platen glass 18 on the second side NHT in the
longitudinal direction. The subscanning-direction abutting portion
54 is formed of a plate-shaped member extending in the transverse
direction of the image reading processing unit 14 (the main
scanning direction SH), and the subscanning-direction abutting
portion 54 is formed so as to have a thickness larger than that of
the platen glass 18.
[0046] An edge 54A of the subscanning-direction abutting portion 54
that is located on the side of the platen glass 18 protrudes upward
further than the glass surface 18A of the platen glass 18 does. The
document, which is the reading target 12, is positioned by causing
a second side 12B of the document to abut against the edge 54A of
the subscanning-direction abutting portion 54, so that the reading
target 12 may be arranged at a predetermined position in the
subscanning direction FH.
[0047] An end portion of the subscanning-direction abutting portion
54 is positioned in a state of being located in a cutout portion
52B that is formed in an end portion of the main-scanning-direction
abutting portion 52, and the edge 52A of the
main-scanning-direction abutting portion 52 and the edge 54A of the
subscanning-direction abutting portion 54 intersect each other at
right angles. Here, the term "at right angles" includes angles
within a manufacturing error range.
[0048] Note that, in the drawings including FIG. 3 that illustrates
the reading target 12, a state in which the sides 12A and 12B of
the reading target 12 are respectively separated from the abutting
portions 52 and 54 is illustrated for convenience of
description.
[0049] In the image reading device 10, a reference portion is
provided in a reading area 56 of the reading unit 22. The reference
portion includes a first main reference line 60 that is provided on
a first side in the main scanning direction SH of the reading unit
22 (a second side THT in the transverse direction) and that forms a
first reference portion and a second main reference line 62 that is
provided on a second side in the main scanning direction SH of the
reading unit 22 (the first side THI in the transverse direction)
and that forms a second reference portion. Each of the main
reference lines 60 and 62 is formed of a straight line, and the
main reference lines 60 and 62 are parallel to each other. Here,
the term "parallel" includes inclinations within a manufacturing
error range.
[0050] In the first exemplary embodiment, although the case in
which the first main reference line 60 and the second main
reference line 62 are each formed of a straight line is described,
the present disclosure is not limited to this case. Each of the
first main reference line 60 and the second main reference line 62
may be formed of a curved line, a bent line, or a dashed line.
[0051] In addition, although the case in which the first main
reference line 60 and the second main reference line 62 are
parallel to each other is described as an example, the present
disclosure is not limited to this case, and the first main
reference line 60 and the second main reference line 62 are not
necessarily parallel to each other.
[0052] The first main reference line 60 is provided on the glass
surface 18A of the platen glass 18 on which the reading target 12
is to be placed. In general, deformation is relatively less likely
to occur in a platen glass than in a housing of a device or a
moving mechanism, and thus, the first main reference line 60 is
provided on the glass surface 18A of the platen glass 18. The first
main reference line 60 may be formed by, for example, printing and
may be provided on the front surface of the platen glass 18 that
forms a portion of the platen glass 18 on the side of the covering
16 or on the rear surface of the platen glass 18 that forms a
portion of the platen glass 18 on the side of the reading unit 22.
In the first exemplary embodiment, a case in which the first main
reference line 60 is provided on the rear surface of the platen
glass 18 from the standpoint of protection of the first main
reference line 60 will be described as an example.
[0053] The second main reference line 62 is provided on the rear
surface of the main-scanning-direction abutting portion 52 against
which the document, which is the reading target 12, is caused to
abut so as to be positioned, the rear surface being located on the
side of the reading unit 22, and the second main reference line 62
may be formed by, for example, printing.
[0054] Note that, although FIG. 3 illustrates a case in which the
second main reference line 62 is provided on the front surface of
the main-scanning-direction abutting portion 52 for convenience of
describing the position of the second main reference line 62, the
second main reference line 62 is provided on the rear surface of
the opaque main-scanning-direction abutting portion 52 and is not
visible from the front side.
[0055] Each of the main reference lines 60 and 62 of the reference
portion is provided so as to be located in a region outside the
peripheral edge 12C of the reading target 12 having a readable
document size when the reading target 12 is set at a predetermined
position. Note that, in the first exemplary embodiment, the reading
area 56 of the reading unit 22 is expanded so as to include
portions of the main reference lines 60 and 62.
[0056] To describe it specifically, in the case where a maximum
readable document size in the image reading device 10 is the size
of an A3 sheet, the reading target 12, which is an A3 document, is
set at the predetermined position by causing the sides 12A and 12B
of the reading target 12 to abut against the edge 52A of the
main-scanning-direction abutting portion 52 and the edge 54A of the
subscanning-direction abutting portion 54, respectively. In this
state, the main reference lines 60 and 62 are located outside the
peripheral edge 12C of the reading target 12.
[0057] FIG. 4 is a diagram illustrating a straight line 64 formed
on the reading target 12 and image data 66 of the straight line 64
acquired by the image reading device 10.
[0058] Distortion may occur in the image data 66 acquired by the
image reading device 10 due to, for example, positional variations
and inclination of the carriages 24 and 26 caused by variations in
winding amounts of the drive wires 40 or deformation of the housing
14A. As a result, distortion occurs in the image data 66 indicating
the straight line 64, and linearity may be determined by using a
distortion width H.
[0059] FIG. 5 is a flowchart illustrating a flow of correction
processing that is performed by the image processing unit 50, and
the operation of the image reading device 10 will now be described
by using the flowchart. Note that, although the image reading
device 10 includes the first main reference line 60 and the second
main reference line 62 as the reference portion, an operation using
only the first main reference line 60 will be described in the
first exemplary embodiment.
[0060] In other words, the image processing unit 50 includes a
calculation unit to which a central processing unit (CPU), read
only memory (ROM), and random access memory (RAM) are connected,
and the CPU operates in accordance with a program stored in the
ROM. For example, upon first energization at the time of shipment,
when a reading switch is operated, correction processing is invoked
from a main routine.
[0061] Then, for example, it is determined whether an initial
value, which will be described later, is stored in a flash memory
that is a non-volatile semiconductor memory included in the image
processing unit 50 (S1). The initial value has not been stored when
the initial energization is performed at the time of shipment.
Thus, the reading unit 22 is operated so as to read the first main
reference line 60, and positional data of the first main reference
line 60 is read and stored as the initial value in the flash memory
(S2). After that, the processing returns to the main routine.
[0062] In this case, as illustrated in FIG. 6, the positional data
that is stored as the initial value includes, for example,
positional data items of measurement points that are set beforehand
on the first main reference line 60 so as to be equally spaced, and
these positional data items, which are stored as initial values,
will be referred to as initial-value data items 1 to 10.
[0063] Then, after starting to use the image reading device 10,
when the reading switch is operated, and the correction processing
is invoked from the main routine, it is determined in step S1 that
the initial values are stored in the flash memory (S1).
Subsequently, the reading unit 22 reads the positional data items
of the measurement points on the first main reference line 60, and
these positional data items are stored as comparative data items 11
to 20 in a memory unit such as the RAM as illustrated in FIG. 7
(S3). In addition, an image of the reading target 12 is also read,
and this read data is stored in the memory unit such as the
RAM.
[0064] Note that the comparative data items 11 to 20 do not need to
be stored for each normal scan operation. For example, the
comparative data items 11 to 20 may be stored when a scan operation
is performed after a certain time has passed, or the comparative
data items 11 to 20 may be stored when a scan operation has been
performed a predetermined number of times.
[0065] Next, the initial-value data items 1 to 10 are subtracted
from the corresponding comparative data items 11 to 20, and a
displacement amount of the positional data item that has been read
at the time of a normal scan operation from the corresponding
initial value is acquired at each measurement point (S4).
[0066] Then, the whole read data acquired by reading the reading
target 12 in the main scanning direction SH is corrected on the
basis of the acquired displacement amount (S5).
[0067] To describe it specifically, the displacement amount
acquired at each measurement point of the first main reference line
60 is subtracted from a corresponding one of read data items of a
first straight line 68A that is provided on the reading target 12,
the one read data item corresponding to the measurement point in
the main scanning direction SH, so that correction data items are
acquired. This arithmetic operation is performed on read data items
of a second straight line 68B and read data items of a third
straight line 68C, so that correction data items are acquired
(generated), and as a result, a corrected image is obtained.
[0068] In FIG. 7, each of the straight lines 68A to 68C of the
reading target 12 extends along the first main reference line 60,
and thus, positional data items obtained by moving the comparative
data items 11 to 20 to the positions of the straight lines 68A to
68C in the main scanning direction SH are acquired as correction
data items.
[0069] Note that values between the adjacent initial-value data
items (1 and 2, 2 and 3, . . . ) for acquiring displacement amounts
are obtained by, for example, interpolation, and the read data
items are complemented by using these acquired data items.
(Comparative Test)
[0070] FIG. 8 is a graph illustrating a result of a longitudinal
linearity test in which the reading target 12 that has a straight
line extending in the subscanning direction FH is read by the image
reading device 10 according to a comparative example 70 that does
not perform the above-described correction processing and a result
of a longitudinal linearity test in which the reading target 12
that has a straight line extending in the subscanning direction FH
is read by the image reading device 10 according to the exemplary
embodiment 72. In FIG. 8, the horizontal axis denotes the number of
documents that have been read, and the vertical axis denotes a
distortion width.
[0071] In FIG. 8, although the distortion width of the comparative
example 70 markedly changes depending on the number of documents
that have been read, no change in the distortion width of the
exemplary embodiment 72 corresponding to the number of documents
that have been read is observed.
[0072] FIG. 9 is a diagram illustrating the reading target 12 that
is used in a right-angle test using the image reading device 10,
and a straight line 74A extending in the main scanning direction SH
and a straight line 74B extending in the subscanning direction FH
are provided on the reading target 12 so as to intersect each other
at right angles.
[0073] FIG. 10 is a graph illustrating a result of a right-angle
test in which the reading target 12 illustrated in FIG. 9 is read
by the image reading device 10 according to the comparative example
70 that does not perform the above-described correction processing
and a result of a right-angle test in which the reading target 12
illustrated in FIG. 9 is read by the image reading device 10
according to the exemplary embodiment 72. In FIG. 10, the
horizontal axis denotes the number of documents that have been
read, and the vertical axis denotes a distortion width.
[0074] It is understood from FIG. 10 that, although the distortion
width of the comparative example 70 markedly changes depending on
the number of documents that have been read, there is a small
change in the distortion width of the exemplary embodiment 72
corresponding to the number of documents that have been read.
[0075] FIG. 11 is a diagram illustrating the reading target 12 that
is used in an oblique linearity test using the image reading device
10, and a straight line 74C extending in a direction that is
inclined with respect to the main scanning direction SH and with
respect to the subscanning direction FH is provided on the reading
target 12.
[0076] FIG. 12 is a graph illustrating a result of an oblique
linearity test in which the reading target 12 illustrated in FIG.
11 is read by the image reading device 10 according to the
comparative example 70 that does not perform the above-described
correction processing and a result of an oblique linearity test in
which the reading target 12 illustrated in FIG. 11 is read by the
image reading device 10 according to the exemplary embodiment 72.
In FIG. 12, the horizontal axis denotes the number of documents
that have been read, and the vertical axis denotes a distortion
width.
[0077] It is understood from FIG. 12 that, although the distortion
width of the comparative example 70 markedly changes depending on
the number of documents that have been read, there is a small
change in the distortion width of the exemplary embodiment 72
corresponding to the number of documents that have been read.
[0078] Note that, in the present exemplary embodiment, although a
case has been described in which read data is corrected on the
basis of an acquired displacement amount, the present disclosure is
not limited to this case.
[0079] For example, error handling may be performed (error handling
unit) when an acquired displacement amount exceeds a predetermined
value. Here, for example, the predetermined value is set within a
range of .+-.0.3 mm. In addition, a displacement amount that is
compared with the predetermined value may be the average value of
displacement amounts acquired at the measurement points or may be
the greatest value among these displacement amounts. In the present
exemplary embodiment, the displacement amount that is compared with
the predetermined value is the greatest value among displacement
amounts acquired at the measurement points.
[0080] Examples of the error handling include activating an alarm
and displaying a message that indicates a need for repair onto a
user interface (UI).
[0081] In this case, at the time of shipment, a grid sample 78 that
has a grid line 76 having a known absolute value as illustrated in
FIG. 13 is read beforehand, and the positional data of the grid
line 76 is stored as grid data into the flash memory. In this case,
in the above-described error handling, the grid data is corrected
on the basis of an acquired displacement amount, so that the
absolute value of read data may be corrected on the basis of the
corrected grid data.
[0082] In addition, in the present exemplary embodiment, although
the first main reference line 60, which is a reference line, is
provided on the glass surface 18A on which the reading target 12 is
to be placed, the present disclosure is not limited to this
configuration.
[0083] For example, the reference line may be provided on the
covering 16, which is configured to be located above the reading
target 12. In this case, the quality of appearance may be further
improved compared with the case where the reference line is
provided on the glass surface 18A on which the reading target 12 is
to be placed.
[0084] In addition, if a reference line having a grid-like pattern
is provided on the covering 16, read data may be corrected on the
basis of the reference line that appears at the outer periphery of
the reading target 12 in a state where the reading target 12 is
covered with the covering 16. As a result, the accuracy of
correction data is improved even in the case where the reading
target 12 has a small size.
Second Exemplary Embodiment
[0085] FIG. 14 to FIG. 16 are diagrams illustrating a second
exemplary embodiment. Components that are the same as or similar to
the components according to the first exemplary embodiment are
denoted by the same reference signs, and descriptions thereof will
be omitted. Only differences from the first exemplary embodiment
will be described.
[0086] In the image reading device 10, read data that is read from
the reading target 12 is corrected by using the first main
reference line 60, which is included in the reference portion, and
the second main reference line 62, which is included in the
reference portion and which is parallel to the first main reference
line 60.
[0087] To describe it specifically, in step S2 of the first
exemplary embodiment, which is illustrated in FIG. 5, the first
main reference line 60 and the second main reference line 62 are
read, and positional data items of the main reference lines 60 and
62 are stored as initial values into the flash memory (S2).
[0088] In this case, as illustrated in FIG. 14, the positional data
items that are stored as the initial values include, for example,
positional data items of the measurement points that are set
beforehand on the first main reference line 60 so as to be equally
spaced, and these positional data items, which are stored as the
initial values, will be referred to as the initial-value data items
1 to 10.
[0089] In addition, the positional data items that are stored as
the initial values include positional data items of measurement
points that are set beforehand on the second main reference line 62
so as to be equally spaced, and these positional data items, which
are stored as the initial values, will be referred to as
initial-value data items 1* to 10*.
[0090] Then, in step S3 of the first exemplary embodiment, which is
illustrated in FIG. 5, the positional data items of the measurement
points of the main reference lines 60 and 62 are read, and these
positional data items are stored as comparative data items 11 to 20
and 11* to 20* in a memory unit such as the RAM as illustrated in
FIG. 16 (S3). In addition, an image of the reading target 12 is
also read, and read data items are stored in the memory unit such
as the RAM.
[0091] Next, in step S4 of the first exemplary embodiment, which is
illustrated in FIG. 5, the initial-value data items 1 to 10 are
subtracted from the corresponding comparative data items 11 to 20,
and a displacement amount of the positional data item that has been
read at the time of a normal scan operation from the corresponding
initial value is acquired at each measurement point.
[0092] In addition, the initial-value data items 1* to 10* are
subtracted from the corresponding comparative data items 11* to
20*, and a displacement amount of the positional data item that has
been read at the time of a normal scan operation from the
corresponding initial value is acquired at each measurement point
(S4).
[0093] Then, the read data items that have been read between the
first main reference line 60 and the second main reference line 62
are corrected on the basis of the displacement amounts. In this
case, the read data items are corrected by using complemented
displacement amounts that have been complemented on the basis of
the relationship between a separation distance X1 from the first
main reference line 60 to the second main reference line 62 and the
distances (XA, XB, XC, etc.) from the second main reference line 62
to the read data items to be corrected.
[0094] More specifically, a case where read data of a position 1 of
the first straight line 68A that is provided at a position A as
illustrated in FIG. 16 is complemented will now be described with
reference to FIG. 15.
[0095] A complemented displacement amount HZ is obtained by
multiplying a subtraction value G, which is obtained by subtracting
a displacement amount (e.g., 11-1) on the first main reference line
60 from a displacement amount (e.g., 11*-1*) on the second main
reference line 62, by a division value, which is obtained by
dividing the distance XA between the second main reference line 62
and the first straight line 68A by the separation distance X1
between the first main reference line 60 and the second main
reference line 62.
complemented displacement amount
HZ={(11*-1*)-(11-1)}><XA/X1
[0096] Then, the complemented displacement amount is subtracted
from the displacement amount (11*-1*) on the second main reference
line 62, and the read data item of the first straight line 68A at
the position A is corrected.
(11*-1*)-{(11*-1*)-(11-1)}.times.XA/X1
[0097] This arithmetic operation is repeated for positions 1 to 10
of the first straight line 68A, and the read data items of the
first straight line 68A at the positions 1 to 10 are corrected.
[0098] Note that read data items between the adjacent read data
items (11* and 12*, 12* and 13*, . . . , 11 and 12, 12 and 13, . .
. ) are corrected by using data items acquired by, for example,
interpolation.
[0099] Then, these arithmetic operations are performed on read data
of the second straight line 68B that is provided at a position B
and read data of the third straight line 68C that is provided at a
position C.
[0100] The read data items that have been read between the first
main reference line 60 and the second main reference line 62 are
corrected on the basis of displacement amounts. In this case, the
read data items are corrected by using complemented displacement
amounts that have been complemented on the basis of the
relationship between the separation distance X1 from the first main
reference line 60 to the second main reference line 62 and the
distances (XA, XB, XC, etc.) from the second main reference line 62
to the read data items to be corrected.
Third Exemplary Embodiment
[0101] FIG. 17 is a diagram illustrating a third exemplary
embodiment. Components that are the same as or similar to the
components according to the above-described exemplary embodiments
are denoted by the same reference signs, and descriptions thereof
will be omitted. Only differences from the above-described
exemplary embodiments will be described.
[0102] In the third exemplary embodiment, the first main reference
line 60 and the second main reference line 62, which are included
in the reference portion, are provided at positions different from
those in the first exemplary embodiment.
[0103] In other words, an opaque non-reading unit 80 that has a
rectangular frame-like shape is formed along the periphery of the
top surface of the image reading processing unit 14. A portion of
the non-reading unit 80 that is located on the first side THI in
the transverse direction of the image reading processing unit 14
includes the main-scanning-direction abutting portion 52, and a
portion of the non-reading unit 80 that is located on the second
side NHT in the longitudinal direction of the image reading
processing unit 14 includes the subscanning-direction abutting
portion 54.
[0104] A frame edge of the non-reading unit 80 on the first side
THI in the transverse direction is formed of the edge 52A of the
main-scanning-direction abutting portion 52, and the second main
reference line 62, which is to be read by the reading unit 22, is
formed of the edge 52A. In addition, a frame edge of the
non-reading unit 80 on the second side THT in the transverse
direction forms the first main reference line 60, which is to be
read by the reading unit 22.
[0105] The main reference lines 60 and 62, which are to be read by
the reading unit 22, are formed of the frame edges of the
non-reading unit 80, and the second main reference line 62 is
formed of the edge 52A of the main-scanning-direction abutting
portion 52, against which the reading target 12 is caused to abut
so as to be positioned. It is desirable that the non-reading unit
80 be black in order to enhance the distinction between the
non-reading unit 80 and a document, which is the reading target
12.
[0106] Note that, in the present exemplary embodiment, although the
main reference lines 60 and 62 are formed by using the frame edges
of the non-reading unit 80, the present disclosure is not limited
to this configuration. For example, the main reference lines 60 and
62 may be formed by using the edges of the platen glass 18.
Fourth Exemplary Embodiment
[0107] FIG. 18 is a diagram illustrating a fourth exemplary
embodiment. Components that are the same as or similar to the
components according to the above-described exemplary embodiments
are denoted by the same reference signs, and descriptions thereof
will be omitted. Only differences from the above-described
exemplary embodiments will be described.
[0108] A first auxiliary reference line 82 and a second auxiliary
reference line 84 each extending in a direction crossing the
direction in which the main reference lines 60 and 62 extend are
provided in the reading area 56 of the reading unit 22 of the image
reading device 10. The auxiliary reference lines 82 and 84 extend
in the main scanning direction SH, in which the full-rate carriage
24 included in the reading unit 22 extends. The auxiliary reference
lines 82 and 84 are each formed of a straight line, and the
auxiliary reference lines 82 and 84 are parallel to each other.
Here, the term "parallel" includes inclinations within a
manufacturing error range.
[0109] The first auxiliary reference line 82 is provided on the
glass surface 18A of the platen glass 18, on which the reading
target 12 is to be placed. The first auxiliary reference line 82
may be formed by, for example, printing, and as an example, the
first auxiliary reference line 82 is provided on the rear surface
of the platen glass 18 that forms a portion of the platen glass 18
on the side of the reading unit 22.
[0110] The second auxiliary reference line 84 is provided on the
rear surface of the subscanning-direction abutting portion 54
against which a document, which is the reading target 12, is caused
to abut so as to be positioned, the rear surface being located on
the side of the reading unit 22, and the second auxiliary reference
line 84 may be formed by, for example, printing.
[0111] Note that, although FIG. 18 illustrates a case in which the
second auxiliary reference line 84 is provided on the front surface
of the subscanning-direction abutting portion 54 for convenience of
describing the position of the second auxiliary reference line 84,
the second auxiliary reference line 84 is provided on the rear
surface of the opaque subscanning-direction abutting portion 54 and
is not visible from the front side.
[0112] The read data items that have been read between the first
auxiliary reference line 82 and the second auxiliary reference line
84 are corrected on the basis of displacement amounts. In this
case, the read data items are corrected by using complemented
displacement amounts that have been complemented on the basis of
the relationship between the separation distance from the first
auxiliary reference line 82 to the second auxiliary reference line
84 and the distance from the first auxiliary reference line 82 or
the second auxiliary reference line 84 to the read data to be
corrected.
[0113] Note that, in the present exemplary embodiment, although a
case has been described in which displacement amounts are obtained
on the basis of the main reference lines 60 and 62 and the
auxiliary reference lines 82 and 84, the present disclosure is not
limited to this case. For example, displacement amounts may be
obtained on the basis of the auxiliary reference lines 82 and
84.
[0114] In addition, a CIS-type scanner may be used in the present
technology.
[0115] The foregoing description of the exemplary embodiments of
the present disclosure has been provided for the purposes of
illustration and description. It is not intended to be exhaustive
or to limit the disclosure to the precise forms disclosed.
Obviously, many modifications and variations will be apparent to
practitioners skilled in the art. The embodiments were chosen and
described in order to best explain the principles of the disclosure
and its practical applications, thereby enabling others skilled in
the art to understand the disclosure for various embodiments and
with the various modifications as are suited to the particular use
contemplated. It is intended that the scope of the disclosure be
defined by the following claims and their equivalents.
* * * * *